Effect of Bentonite on Nitrogen and Mineral Balances and Ration Digestibility of High-Grain Rations Fed to Lactating Dairy Cows

Abstract

A digestion trial was conducted with lactating Holstein cows fed the following rations: I) a high-grain, fat-depressing ration; II) fat-depressing ration + 5% sodium bentonite; and III) fat-depressing ration + 10% sodium bentonite. The mean adjusted dry matter digestibilities of I) 78.7%, II) 80.8%, and III) 76.5% were not significantly different. A nonsignificant increase in nitrogen retention with a significant decrease in crude protein digestibility was noted with both of the bentonite treatments. The mean protein digestibilities (%) and daily nitrogen retention (g/day) for the treatments were: I) 79.9 and 37.2; II) 75.4 and 75.9; and III) 68.8 and 53.0, respectively. Energy digestibility decreased significantly. Mean digestible energy (%) for Treatments I, II, and III were 78.4, 71.8, and 69.1. Calcium, phosphorus, and magnesium balances (g/day) were as follows: I) 31.6, 33.0, 8.2; II) 9.5, 9.4, 2.1; and III) 3.1, -3.4, 1.5. Differences between I versus II and III as well as II versus III in phosphorus balance were statistically significant. © 1970, American Dairy Science Association. All rights reserved.